1. Field of the Invention
The present invention relates to the field of screen protectors for touch screen displays, and more particularly to a removable, repositionable protective film for a touch screen display.
2. Brief Description of the Related Art
Touch screens are widely used, including in portable electronic devices, such as, cellular telephones and portable computing devices, including readers and tablets, such as the popular iPad®. A factor owing to the popularity of these electronic touch screen devices is their portability. The devices are generally lightweight, or compact. As a result, users often carry and use these electronic devices when traveling or when participating in daily activities. In many cases, the touch screens of these electronic devices come in contact with other objects and items, and may be prone to being scratched. In the case of cellular telephones, a user may place the phone in the user's pocket or purse along with potentially other sharp items, such as, for example, keys, nail files, key chains, coins, pens and other objects. There is a need to protect the screens of these electronic devices, and prior art devices have used a film that is placed on the screen surface, the film being attached to the surface statically or with the use of an adhesive.
There are drawbacks with the prior screen protectors. Screen protectors require that the screen surface be cleaned and that it be free from any dust or debris. The presence of dust or other particles on the screen surface will come between the screen protector and the touch screen surface and impair or compromise the viewing quality. If dust particles are present, often the screen protector is raised by the dust particle to be off of the surface of the touch screen. This results in an occurrence of what may be referred to as “tenting” around the dust particle, creating a bubble. The bubbles created impair the viewability of the screen, as the bubbles may be noticeable and interfere with a user's ability to view the screen in those locations where the bubbles are present. In addition, the presence of bubbles may hamper the ability of the screen protector to remain secured to the screen surface.
U.S. Patent Application 2012/0043015, published on Feb. 23, 2012, discloses a method and apparatus for protecting an electronic device. The '015 disclosure specifies an adhesive and a mechanical smoothing device (i.e., a squeegee) for applying the film onto a screen. In addition, the '015 method and apparatus require the elimination of debris and fingerprints prior to applying or reapplying the film. Aside from being time consuming to use and apply because the display surface must be cleaned before the film is installed, in environments where dust is present, such as, on a battlefield, in a war zone, factory, or other locations where cleaning items are not readily available or practical to use, the '015 device and method are not suitable. Another aspect of the '015 apparatus is that the film is disclosed to be elastic and highly conformable so that the film may be applied to complex geometries.
U.S. Patent Application 2007/0077420, published on Apr. 5, 2007, discloses a polyether aliphatic urethane film for protection of exposed surfaces of automobiles, trailers and boats that may come into contact with environmental hazards (such as dirt, dust, rocks, sand road salt, bird droppings). The '420 application discloses a base layer that may be a polyether aliphatic urethane, and a base layer that may be made of laminated or combined layers. The '420 application discloses a topcoat that may be applied to the base layer and which may comprise a resin. The application of the '420 protective film is designed for automobiles, including the leading edges of automobile hoods.
U.S. Patent application 2011/0267793 published on Nov. 3, 2011 discloses a protective adhesive film polyurethane sheet with a pressure-sensitive adhesive that includes an acrylate polymer and a silicone macromer disposed on a portion of the first surface of the polyurethane sheet. The '793 application also discloses using a smoothing device to apply the film to a surface. The presence of dust or debris generally will interfere with the smoothing device, and, in many instances, when dust is present on the screen surface, the film is required to be removed, the screen cleaned, and the film reapplied. In many cases, the film may be compromised and cannot be reapplied due to surface dirt becoming embedded on the film surface. Consequently, a new sheet of film is needed when the film becomes compromised. Even fingerprints may cause problems in applying films to a display surface.
U.S. Pat. No. 7,070,837, issued on Jul. 4, 2006, discloses a screen protector for preventing interference patterns (e.g., Newton rings) from arising when the film touches the screen. The '837 patent discloses a hard plastic film, such as PET, is used as the protective film, and a non-uniform urethane resin is disposed on a lower surface in contact with the screen. The '837 device provides a roughened surface on the film so that the majority of the film surface facing the screen does not substantially touch the screen. The '837 disclosure also specifies that no adhesive or adhesive forces are used to hold the film to the screen.
U.S. Patent Application 2011/0043727 published on Feb. 24, 2011, discloses an adhesive layer for multilayer optical article. The adhesive layer is disposed between optical article's multilayer optical film and the light transmissive support layer of a display, such as an LCD television. The '727 discloses the use of glass as a potential component of the multilayer optical article and is part of an article that is assembled as a display device. In addition, the '727 application discloses a method of making display devices including the optical article.
U.S. Patent Application 2011/0129643, published on Jun. 2, 2011, discloses a surface protective sheet for a metal plate, a resin plate or glass plate that includes a high tack adhesive or high anchoring force, and that provides a preferred haze value of 20% to 80%. The '643 disclosure identifies two outer layers of polyethylene which sandwich a middle mechanical property control layer that may consist of urethane.
One attempt to address the presence of dust particles has been disclosed in U.S. Pat. No. 8,044,942, issued on Oct. 25, 2011, for a touch screen protector which provides a spacer along an outer perimeter of a plastic film surrounding a transparent window and having a thickness sufficient to space the plastic film near but not in contact with the touch screen.
There are drawbacks with the prior devices, and none of the prior devices has been found to be completely suitable. A need exists for an improved touch screen protector that can be readily and easily applied to and removed from a touch screen surface in conditions of uncontrolled environments without compromising the optical quality.